[lumpypua]

I did't mean anything special about it in conjunction with magnesium, just that glycine itself is inhibitory:

https://en.wikipedia.org/wiki/Glycine#As_a_neurotransmitter

> Glycine accomplishes several functions as a transmitter in the central nervous system (CNS). As an inhibitory neurotransmitter, it participates in the processing of motor and sensory information that permits movement, vision, and audition. This action of glycine is mediated by the strychnine-sensitive glycine receptor, whose activation produces inhibitory post-synaptic potentials. In some areas of the CNS, glycine seems to be co-released with GABA, the main inhibitory amino acid neurotransmitter. In addition, glycine modulates excitatory neurotransmission by potentiating the action of glutamate at N-methyl-D-aspartate (NMDA) receptors.

https://www.ncbi.nlm.nih.gov/pubmed/11396606